Ryan,
When I cook ribs I never foil them, not because I don't like fall of the bone( I do infact like fall of the bone) it is because I practice for competitions. I have only had my WSM for about two months now and used it about 10 times( I also have an offset and a brinkmann bullet). The 2nd time I used the WSM, I cooked 3 racks of spares which I trimmed myself, the were the best ribs I have ever done in the 6+ yrs I've been BBQing.
I prepped the ribs the night before, and let them sit in the dry rub over night. the next day I used 1 full chimney of unlit charcoal, 1/2 chimney of lit, and about 4 chunks of hickory. The cooker temp. was about 240. I put the ribs on and cooked them for 4 hrs, the last hr I glazed them with KC masterpiece original and honey(very common and easy). The meat did not fall of the bone, rather it could be bitten off easily with only the place that was bitten came off. they were very tender and juicy. hope that this helps.